Mineral oil composition



' Patented July 8, 194 1 IMINERAL 01L CQMPOSITION Bulkley, Pitman, Lyle A. Hamilton, Wenonah, and Vladimir A. Kalichevsky, Woodbury, N. J., assig'nors to Socony-Vacuum Oil Company, Incorporated, New corporation of New York York, N. Y., a

No Drawing. Application January 24, 1939, Serial No. 252,542

21Claims.

This invention is directedto the stabilization of hydrocarbon oils of higher boilng pont, such as lubricating oil fractions, against the detericrating effects of oxidation. Refined oils of the type of turbine oils and-the like must be able towithstand the conditions under which they are used without formation of acidic products of a nature corrosive or otherwise damaging to the metal structures to be lubricated by those oils; Moderately refined oils of the nature of many common lubricating fractions must be able to withstand the conditions of their use without the development of similar acidic products. Such acidic products apparently arise from an ogygenation of the oil under its condition of use. This invention is directed to the stabilization against deterioration due to oxidation reactions of any petroleum fractions of a light lubricant nature or heavier, including the variously moder-.

ately refined oils, and also inclusive of more.

highly refined oils such as turbine oils and the like.

This invention has for an important object the preparation of oils falling within the above classes which are stable againstoxidation or capable of meeting normal conditions of their use without the formation of materials of an acidic or corrosive nature. I F

It is known that recent changes in automotive engine design are tending toward higher bearin: pressures. higher rotativespeeds, higher enfline temperatures, and are accompanied by the use of bearing metals less resistant to corrosive materials than those normally used under conditions which are not so prone to develop corrosive oxidation products .in the oils. It is also known that an increasing proportion-of lubricant oils for all purposes are manufactured by processes of solvent refining or solventextraction products of a corrosive nature to bearing metals under conditions of use. This invention is directed to the inhibition of the formation of such acidic reaction products.

We have found that hydrocarbon oils of the contains certain sulfonic acids which are pre- 1s ionic acids."

- holic solutions and may subsequently be recov-' classes defined above, can be stabilized against the formation of acidic reaction products under conditions of use by the addition thereto'of relatively minor amounts of oil-soluble sulfonic acids.

The sulfonic acids contemplated are those products which are formed when treating a petroleum lubricant fraction withrelatively strong sulfuric acid, such as for example with oleu'm. In thecourse of such treatment, as is well known, there are formed sludges and sulfonic acids of various kinds. The sludges, together with the unconsumed acid; are separated from the oil by gravity. This sludge mixture dominantly of the kinddeflned'as "green sul- These green sulfonic raeids tend to be more water-soluble than oil-soluble. In the oil which remains after the sludge is withdrawn, there are dissolved other 'sulfonic acids oil-soluble in nature and generally referred to by the collective terms brown or mahogany sulfonic acids." These oil-soluble sulfonic acids may be recovered by separating them from the oil with an alcohol or with an aqueous alcoholic solution or by neutralizing with an alkali after which the alkalinesoaps of sulfonic acids are separated by means of alcoholor aqueous alcoered from the solution of acids .or solutions of soaps by known processes of acidification, salting out, and dehydration. This invention is directed jecting it to conditions appropriate for 'its degradation. The neutralization number is defined as themilligrams of hydroxide required to neutralize the acids formed in one gram of oil. As an indication oi the eificiency of these inhibitors, there may be cited thefollowin examples:

Example I An oil of the type used in transformers had been highly refined by means of sulfuric acid to a specific gravity of .871, a flash point of 310 1'.

and a Saybolt viscosity of 69 seconds at 1''. It

was tested by heating loo grams to C., and

determining the neutralization number of the range we may use from 0.001% to 0.10% by oxidized oil. weight.

N. N. We claim Q11 alone 239 1. A lubricating oil composition relatively 034.40% ulfonl acids 0, 5 stable against the formation of acidic products o ulfonic acids 2, of oxidation comprising a completely refined Example II A second oil of asaybolt viscosity of 159 second at 100 F. and a flash point of 410 F. had

been moderately refined by means of a solvent. It was tested by heating to 110 C. for three days in the presence of a piece of copper foil and then determining the neutralization number 01' the oil.

N. N. Oil a1one 0.19 Oi1+.10% suifonic acids '0.l1

lubricating oil which is not so stable, and which 011 is initially free or any acidic constituents, and in addition thereto a controlled small amount but not in excess of about 0.5% by weight of oil soluble sulphonic acids derived from the treatment of lubricating oil fractions with relatively strong sulphuric acid.

2.- A lubricating oil composition relatively stable against the formation of acidic products of oxidation comprising a completely refined lubricating oil which is not so stable, and which oil is initially free of any acidic constituents, and in addition thereto a controlled small amount from 0.001% to 0.10% by weight of oil soluble Sui-phonic acids derived from. the treatment oi. lubricating oil fractions with relatively strong sulphuric acid.

RONALD BULKLEY.

LYLE A. HAMILTON.

VLADIMIR A. KALICHEVSKY. 

